Process sequentially special branch fBranchRef.
Process sequentially special branch fBranchRef.

As pointed out by Philippe: if requested by the user, a special branch (recorded in
TTree::fBranchRef) is created that keeps track of which branch contains objects that
are 'referenced' by TRef. Upon reading and then dereferencing of a TRef object,
TRef::GetObject is called which turns around and calls TBranchRef::Notify which will
call GetEntry on the branch.

There might be a race condition in the multi-threaded TTree::GetEntry if TRef::GetObject
is called during its execution. This is possible if the user inserts schema-evolution
rules that use the TRef. So it might be wise to pre-emptively load the TBranchRef in the
sequential section.

bbockelm/root,zzxuanyuan/root,zzxuanyuan/root,olifre/root,bbockelm/root,root-mirror/root,mhuwiler/rootauto,BerserkerTroll/root,olifre/root,simonpf/root,BerserkerTroll/root,karies/root,zzxuanyuan/root,root-mirror/root,davidlt/root,agarciamontoro/root,root-mirror/root,BerserkerTroll/root,olifre/root,olifre/root,mhuwiler/rootauto,root-mirror/root,karies/root,karies/root,davidlt/root,zzxuanyuan/root,bbockelm/root,davidlt/root,mhuwiler/rootauto,davidlt/root,bbockelm/root,mhuwiler/rootauto,olifre/root,bbockelm/root,mhuwiler/rootauto,agarciamontoro/root,agarciamontoro/root,simonpf/root,BerserkerTroll/root,simonpf/root,mhuwiler/rootauto,karies/root,simonpf/root,davidlt/root,agarciamontoro/root,mhuwiler/rootauto,simonpf/root,bbockelm/root,karies/root,davidlt/root,simonpf/root,simonpf/root,root-mirror/root,zzxuanyuan/root,simonpf/root,root-mirror/root,olifre/root,davidlt/root,root-mirror/root,bbockelm/root,davidlt/root,mhuwiler/rootauto,root-mirror/root,bbockelm/root,zzxuanyuan/root,karies/root,mhuwiler/rootauto,mhuwiler/rootauto,simonpf/root,olifre/root,karies/root,agarciamontoro/root,simonpf/root,davidlt/root,agarciamontoro/root,olifre/root,BerserkerTroll/root,davidlt/root,BerserkerTroll/root,bbockelm/root,BerserkerTroll/root,zzxuanyuan/root,agarciamontoro/root,olifre/root,agarciamontoro/root,bbockelm/root,olifre/root,BerserkerTroll/root,root-mirror/root,zzxuanyuan/root,bbockelm/root,agarciamontoro/root,root-mirror/root,karies/root,karies/root,zzxuanyuan/root,agarciamontoro/root,zzxuanyuan/root,zzxuanyuan/root,BerserkerTroll/root,simonpf/root,olifre/root,zzxuanyuan/root,karies/root,root-mirror/root,davidlt/root,BerserkerTroll/root,BerserkerTroll/root,mhuwiler/rootauto,karies/root,agarciamontoro/root